As Saudi troops swept into Bahrain on Monday, President Obama kept playing his favorite new role: the Invisible Man.

Bahrain is a key US ally and headquarters to the Navy’s Fifth Fleet, which patrols the Persian Gulf and Indian Ocean from the Horn of Africa to Bangladesh.

But its Sunni monarchy sits atop a restive Shia majority. So the Saudis sent in about 2,000 troops to assert order, lest Iran make the island another cat’s paw.

The United States could have headed off the protests, pressuring Bahrain to create a legitimate parliament and grant Shias political power. Instead, Obama ducked — and created a vacuum that the Saudis felt compelled to fill.

The White House, seemingly paralyzed by doubt and indecision, has been mute since.

“This is not an invasion of a country,” stuttered press secretary Jay Carney on Monday.

Alas, dithering is not a foreign policy — and the world keeps turning, even as President No-see-um stands mute.